Biofilm origin of clay-coated sand grains

Wooldridge, L.J., Worden, R.H., Griffiths, J., Thompson, A. and Chung, P. (2017) Biofilm origin of clay-coated sand grains. Geology, 45(10), pp. 875-878. (doi: 10.1130/G39161.1)

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The presence of clay-sized particles and clay minerals in modern sands and ancient sandstones has long presented an interesting problem, because primary depositional processes tend to lead to physical separation of fine- and coarse-grained materials. Numerous processes have been invoked to explain the common presence of clay minerals in sandstones, including infiltration, the codeposition of flocculated muds, and bioturbation-induced sediment mixing. How and why clay minerals form as grain coats at the site of deposition remains uncertain, despite clay-coated sand grains being of paramount importance for subsequent diagenetic sandstone properties. We have identified a new biofilm mechanism that explains clay material attachment to sand grain surfaces that leads to the production of detrital clay coats. This study focuses on a modern estuary using a combination of field work, scanning electron microscopy, petrography, biomarker analysis, and Raman spectroscopy to provide evidence of the pivotal role that biofilms play in the formation of clay-coated sand grains. This study shows that within modern marginal marine systems, clay coats primarily result from adhesive biofilms. This bio-mineral interaction potentially revolutionizes the understanding of clay-coated sand grains and offers a first step to enhanced reservoir quality prediction in ancient and deeply buried sandstones.

Item Type:Articles
Additional Information:This work was carried out as part of the Chlorite Consortium at Liverpool University (UK), sponsored by BP, BG, Shell, Eni, Statoil, Petrobras, Woodside, and Chevron oil companies.
Glasgow Author(s) Enlighten ID:Chung, Mr Peter
Authors: Wooldridge, L.J., Worden, R.H., Griffiths, J., Thompson, A., and Chung, P.
College/School:College of Science and Engineering > School of Geographical and Earth Sciences
Journal Name:Geology
Publisher:Geological Society of America
ISSN (Online):1943-2682
Copyright Holders:Copyright © 2017 The Authors
First Published:First published in Geology 45(10): 875-878
Publisher Policy:Reproduced under a Creative Commons license

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